Automatic motor-starting rheostat.



v I P. ZIMMER.

AUTOMATIC MOTOR STARTING. RHEOSTAT.

- APPLICATION FILED FEBJO, 1905. r 1,021,227, Patented Mar. 26,1912.

2 SHEETS-SHEET 1v,

Witnesses Ihventdr':

4 I 2 Paul Z i-mmer,

APPLICATION FILED PEBJQ, 1905 Patented Mar. 26, 1912.

2 8EEETSSHEET 2;

Witnesses:

Inventor;

R e .m 2 m. a P

UNITED STATES PATENT OFFICE.

PAUL ZIMMER, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

AUTOMATIC MOTOR-STARTING RHEOSTAT Specification of Letters Patent.

Patented Ma1a26, 1912 f Application filed February 10, 1905 Serial No. 245,014.

To all whom it may concern.

Be it known that I, PAUL ZIMMER, a citizen of the United States, residing at Schenectady, county of, Schenectady, State of New York, have invented certain new and useful Improvements in Automatic Motor- Starting Rheostats, of which the following is a specification.

This invention: relates to motor-starting devices for automatically starting an electric motor and bringing it up out endangering its OOIlS by the admission of too great a current thereto.

More specifically my invention relates to automatic motor starting rheostats in which a resistance in series with the motor armature is gradually and automatically cut out as the 'motor speeds up, and one object of my invention is to reduce the energy loss in the operating coil of the rheostat. Automatic motor-starting rheosta-ts, as constructed prior to my invention, have been provided with a rheostat arm movable over con tacts connected to a resistance, and an actuating solenoid to move the arm to cut the resistance out of circuit against the tension of a retracting spring. In order thatthe armmay not move'too rapidly over the contacts, a dash-pot has been providedto retard this movement. The parts are so adjusted that it takes the rheostat arm from thirty seconds to two or --three minutes to move from the full ofi' to the full on position, as a more rapid movement of the arm would cut out the resistance too rapidly and admit a dangerously large current to the The actuating solenoid being in circuit during this entire period until at the endof the movement it is cut out by an auxiliary switch, the energy loss therein is comparatively large.

In accordance with my invention 1 provide a spring or equivalent means for giv' ing the 'arm a bias in a direction to cut out the resistance and an operating solenoid to move the arm to cut in the resistance and put the spring under tension. I may also provide means, as, for lnstance, a d-ashpot.

to retard the movement of the arm as it moves in response to its bias to cut out resistance. When the solenoid has moved the arm to the proper position and the spring is placed under suitable tension, the solenoid is cut out ofcircuit and the arm returns in response to its :bias under the retarding to speed withinfluence of the dashpot, if such be provided. In ractice I find that in less than one-tenth of a second the core of the solenoid is drawn up, the spring compressed and the solenoid circuit opened so that a great saving in the energy consumed is effected, Moreover, as the solenoid is in circuit for 'onl'y'so short a period, its coils may be of wire of much smallerv cross-section than could be used if; it remained in circuit for the longer period as the heating is practically inappre -iable. Furthermore,- the re sistance is always out out at the same rate irrespective of variations of voltage.

Another object of my invention is to provide a simple, durable and reliable automatic motonstarting rheostat which shall be inexpensive to manufacture.

These and other objects of the invention will more fully appear in the following description. a

The novel features'of my invention will be definitely indicated in the claims appended hereto.

In the accompanying drawings, I have illustrated diagrammatically two embodiments of myinvention but it must be understood t-hat the principle of my invention as set forth in the claims are also applicable to automatic starting devices widely different therefrom I In the drawings, therefore, Figure 1 is a diagrammatic elevation partly in section of one form of my invention: and Fig. 2 is a similarview ofa modified form.

Referring first to Fig. 1. of the drawings, 1 indicates a rheostat arm pivoted at 2 and adapted to,eugage a plurality of contact studs 3, which are connected at intervals to a resistance 4. Thearm 1 is moved over the studs 3 by a member 5 which constitutesthe core of a solenoid 6 Coiled about the'core 5 is a spring 7 which'is -ada-pted-to be compressed between one of the heads of the solenoid and a washer 8 secured on the core.' This spring renders the action of the arm and core more positive than as if the force of grai-ity were depended upon to return them, and in some cases, therefore. the spring may be dispensed with. The lower end of the core 5 forms the piston of a dashpot 9, which is arranged in any usual 'mar ner to retard the movement 'of the piston into the cylinder. of the dash-pot, but is permitted to be drawn out of the cylinder resistance cut out tion,

freely. .The position of therheostat arm 1 illustrated in the drawing'is that which it occupies when all circuits are open and also when all circuits have been closed and the and the motor is runnin at normal speed. If the motor is at rest, an it is desired to through the solenoid core 5 immediately, as not act to retard this movement, thusut-- ting the spring 7 under compression. his moves the rhostat arm 1 back to the position in which the maximum resistance is cut into the motor circuit, and an auxiliary switch then operates to close the motor cirsuit and open the circuit of the actuating coil 6. When this occurs the spring 7 moves 6, which draws up the the dash-pot 9 does the arm 1 back to the on position but this .movement is a slow oneas it is retarded by the dash-pot and therefore the resistance is gradually cut out of the motor circuit and the motor is brought up to speed without danger of injury'th ereto.

The auxiliary switch for closing the motor circuit and opening the circuit of the actuating coil 6 comprises two pivoted switch-blades two switch-clips 11 and 20. Blade 10 is provided with an extension 12 on the other side of its pivot which extends into the path of movement of a projecting portion 13 of the washer 8 The projection 13 is insulated in an suitable 'man1rer, as by a strip of fiber 1 1.- The blade 10 carries an armature 15 which 'coiiperates with a retaining magnet 16 mounted in position to hold the blade 10 when the magnet is energized and the end of the-blade is in the clip 11. A retracting spring 17 has one end attached to the blade 10 and the other'to a fixed post, and serves to return the blade to the position shown in full lines when the retaining magnet- 16 is deiinergized. The blade 10 controls the motor circuit,-and in order that the circuit of solenoid 6 will not be opened until the rheostat arm 1 has reached the full off posiand to obtain a quick break'of the solenoidcircuit, I provide a second ,blade 18 pivoted at the same point as the blade 10, and arranged to be actuated by the blade 10 just as it reaches its final position. 1 Blades 10 and 18 are connected by a spring 18), and a switch-clip 520 is mounted in position to be engaged by them when in the retracted 'position. The ends of blades iOand '18 are cut oil at such an angle that just as the blade 10 is reaching its final position. the

two edges come into cngagcmcnt and blade ,res ect-ively of an electric motor which is start it, circuit is closed 10 and 18 arranged to enter .rclardcd by the dash-pot- 9.

and 23 a line switch which may be I energy,

at a point distant. from the motor, if

located desired.

24 and 25 indicate the armature and field to e automatically started by the rheostat.

The circuit of the motor armature 2 1 is completed from themain 21 through the armature,lso much of resistance 4: as is cut in circuitby the rheostat arm, through the arm 1, and if desire'd,"through an overload coil 26 controlling the no-voltage release magnet 16, to the SWlt'Ch-Cllp 11. Switch-blades 10 and 18 are connected to the negative main 22, so that when the blade 10 enters clip 11, the armature circuit is closed. The field 25 of the motor is connected across the lines so that the motor field is energized as soon as switch 23 is closed. The actuating coil6 is connected between the positive main 21 and the switchclip 20 so that when the blade 18 leaves the clip 20, thecircuit of the coil is opened.

The operation of the device as thus constructed will now be described.

In order to start the motor, the line switch 23 is closed, thus closing the circuit of the motor field 25 and the actuating coil 6 and the latter, being energized, draws up the cdre 5 to compress spring 7 and set the parts in position for starting. This movement is a very rapid one, as itis not retarded by the dash pot'9. -Drawing core 5 up, pulls the rheostat arm 1 back over the contacts until it isin engagement with the first stud 3, or if desired, an open-circ niting stud or segment so that it is now safe to close the motor circuit. Also, when .core5 moves upward, the projection 13 on the washer S engages the extension on the end of blade 10, turnin the blade on its pivot'againstthe tension 0 spring 17 until it enters the clip 11, where it is held by the retaining magnet 16 which, as is seen, is connected across the lines. As blade 10 is nearing its final position, it forces the blade 18 out of clip 20, and spring 19 quickly draws blade 18 up to it, so as to give a quick-break of the circuit of solenoid 6 at the clip 20. When this occurs the spring 7 moves the core 5 back to its original position, thus moving the rheostat arm 1. over the contacts 3 to cut the resist mature 21. but this movement is a slow one.

as movement of core 5 in this direction is The daslnpot may be so constructed as to give any desired time interval between the on and oil positions. It is evident. therefore, that the operating solenoid 6 is in circuit only for a very short. interval. so that there is little loss of energy in the operating coil and the wire from which it is wound may be of much smaller cross-section than would be permissible ifthe coil were allowed to remain in circuit longer. In the event of an opencircuit or an abnormal fall in the voltage,

, '26 would raise its core, thus opening the cirlength that it "normal position until the contact 33.

cuit ofthemagnet 16 with the same result.

I Fig. 2 shows. an automatic motor-starter embodying myinvention, but difi'ering in details of construction from that shown in Fig. 1 This form of my invention possesses the advantages that it is somewhat simpler and somewhat cheaper to construct than that shown in Fig. 1. Instead of the spring 7 coiled about the core 5, a spring 30 coiled about the pivot on the rheostat arm lis employed. The auxiliary switch for closing. the snotor circuitand opening the circuit of the operating coil consists of a single blade 31 instead of the switch of the double-blade type, and a spring 32 coiled about the pivot of this blade is employed to retract the arm. Two contacts 33 and 34 are mounted at the limits of movement of the arm 31, and a bridge of fiber 35 is provided to support the switch-arm \vheh moving from onecontact to the other; In order to maintain the continuity of the operating coil circuit 'until the arm 31 reaches the on position and then effect a quick break of thecircuit, a pivoted contact arm 36 is provided. having springs 37 and 38 coiled about its pivot and acting on the arm in opposite directions to normally center it in the position illustrated in the drawing. One. terminal of the operating. coil6 is connected to the contact 33 and also to the contact arm 36. Arm 3 3is so positioned that it is engaged by the switch arm'31 before the latter leaves the stud 33,

in order to maintainthe continuity of the circuit, and it is of such a is released by the switch arm 31 and snaps back to its normal position just as the arm reaches its final position where it is held by the retaining magnet 16.

necessary the contact. 33 may be-elongated into the form of a segment so that, when arm 31 is retracted to the oft position against a stop 39, it will not release the arm 36 and permit it to be returned to its arm 31 engages In the drawing I have shown operating coil the magnet 16 connect-ed in series with the motor field 25 across the lines, instead of directly across the lines, as in Fig.1; and

' no overload coil is shown in this figure. The

arrangement of-these parts may he changed as desired. The operation of this embodiment of my invention is essentially the same as that shown in Fig. 1. On closure of the line switcl1,'the circuit of the operating coil 6 is closed from main 21 through the coil to contact 33 and through switch arm 31 to main 22. The coi1-6, being energized, draws 'tion in its application up its core 5, thus moving arm 1. to. the ofi' position. As it is drawn up, the insulated projection 13 on the core engages the extension of switch arm 31 and turns the-arm on its pivot. Before leaving the stud33, arm 31 engages the spring-positioned contact arm 36, so that the operating coilcircuit is'maintained closed as the switch arm moves toward contact 34. Just .asthe arm reaches its final position, Where it -,is heldv by the magnet 16, and where it closes, the circuit of the motor armature '24, it disengages the contact arm 36 and the latter is returned to. its normal position by the spring 37, so that the operating coil circuit is now open. This is the position illustrated in the drawing, The spring 3 0 now moves the arm 1 back over the conmcts 3.to.cut the resistance out of the circuit of the motor armature, and as the dashpot 9 retards this; movement, the current is admitted -'to the motor armature at just the proper rate; Other modifications than those/which I have shown may be employed and it should be understood that '-I do-not limit-'myinvento resistance as,distinguished from reactance or transformercoils nor-to-the particular arrangement or construct-ionofmy device, but only as it is limitedloy thes'cope of the claims annexed to and fonninga'part of this application. I

What I claim as new and desire-to secure v by Letters Patent of the United :States, is,

1. An automatic rheostat comprising an arm movable to vary the resistance in circuit, means for moving the arm to cut out the resistance, an-electro-magnetic device to automatically set the arm in position for starting and put said means in an operative position, and means for'deenergizing said device when t'hefactuating""means has been put into operative position. i 1

2. An automatic rheostat comprising an arm movable to vary the resistance in circuit, a spring to move the arm in a direction to cut the resistance out of circuit, an electroma'gnetic device for putting the spring under tension, and means for deenergizing said device when thespring has been put under tension.

An automatic rheostat comprising an arm movable to varythe resistance in, circuit. a spring to. move the arm in a direction to cut the resistance out of circuit, means to retard movement of the arm .in that dire'c tio'n, a solenoid, for putting the spring'under' tension. and means to cut the solenoid out of circuit to decnergize thesame when the spring has been put under tension;

4. An automatic rheostat comprising an arm movable to vary the resistance in circuit, a spring to move the arm in a direction to cut the resistance out of circuit, an electromagnetic device for putting the spring under tension, and means for effecting a 45 motor connprisingr an arm movable to varv to cut the resistance out of circuit, electrithe spring has been put under tension.

.to cutout the resistance, an electromagnetic for rendering said derives inoperative to more. the arm in a direction quick break of the circuit of said device to deenergize the same when the spring has been put under tension.

5.'An automatic rheostat con-iprising an arm movable to vary the resistance in circuit, a spring to move the arm in a direction to cut the resistance out of circuit, means to retard movementof the arm in this direction, electrically controlled devices for putting the spring under tension, and means for rendering said devices inoperative when the spring has been put under tension.

6. An automatic rheostatv comprising an arm movable to vary the resistance in cir cuit, a spring to move the arm in a direction callycontrolled devices, for moving the arm in a direction to cut in the resistance and for putting the spring undertension, and means for rendering said devices inoperatire when the rcsistancehas been cut into circuit.

7. An automaticrheostat comprising an arm movable to vary the resistance in circuit a sprint to move the arm in a direction device for moving the arm in a. direction to out in the resistance and for putting the spring under tension, a dash-pot arranged to retard movement of the arm in a direction to out out the resistance but permit free movement otthearm 1n the opposite dlrection, and means for deenergizing said has been out into circuit.

8 An automatic rheostat for an electric motor comprising anfiarm movable to vary the resistance in the motor circuit. a spring to move the arm in a directionto out out the resistance, electrically, cont-rolled devices for putting: said spring: under tension and then closing the motor circuit. and means for rendering said devices inoperative when 9. An automatic rheost atfor an electric the resistancein the motor circuit. a spring to move-the arm in a direction to ("at out the resistance. eloctricall controlled devices for moving the arm tocut in the resistance and for putting the sprina" under tension. means for closing the motor circuit when the resistance has been cut in; and means when the resistance has been out into circuit.

10.:\n automatic rheostat for an electric l motor comprising an armmovablc to vary the resistance in the motor circuit a. spring to cut out the resistance. a solenoid for moving the arm to out in the resistance. and for putting the position;

.clement therefor having:

spring under tension. :1 switch operated by 1 the solenold to ciose the-motor circuit when l the resistance has been cut in, means for deenergizing the solenoid when the resistance has been cut in, and a dash-pot to retard movement of the arm to cut out the resistance.

11. .Anautomatic rheostat for an electric motor comprising an arm movable to vary the resistance in: the motor circuit, aspring to move the arm in a direction to cut outthe resistance, a solenoid for moving the arm to'cut in the resistance andfor putting the spring under tension, a switch operated by the solenoid to close the motor circuit when the resistance has been cut in meansoperated by the solenoid for opening the solenoid circuit with a quick-break when the resistance has been cut in, and means to retard movement of the switch arm to cut out tlie'resistance. i

12. An automatic motor starter comprising a series of c0ntacts, 'a circuitcontrolling clement therefor having a. bias to running an electrically controlled device for moving said element to starting; position andmeans for denergizing said device when said element reaches the starting position.

13. An automat c motor starter-comprisin o; a series of contacts, a circuit controllingelement therefor having a bias to'running position. an'electricallv controlled device for moving said element to means for closing the motor circuit when the said element reaches starting position and simultaneously (lo-energizing saidv electricallyrontrolled device.

14. An automatic motor starter comp-rising a series of contacts, a circuit-controlling clement therefor having a. bias to running position. an electrically controlled device for inorinn' said element to starting positioin means for deimergizine; said device when said clement reaches the starting position, and means for retarding; said controlling element as it moves toward running position.

it. t ion a series of contacts.

An automatic motor starter comprisa circuit-controlling a bias to running position. an electrically controlled device for moving said element to starting position. ineansiior closing the motor circuit when the said element reaches the starting positiou and sinmltaneouslv 'deenernizing sai electrically controlled device, and means for retarding said controlling element as it moves toward running position.

In Witness Whereofll have hereunto set luv hand this 8th. day of February's 1905.

PAUL ZIMMER.

, lVitnesses:

BEXJATM'IN E. Hunt, Hn'nnn Onronn.

copies of this patent may be obtained 01 five cents each, by addressing the Commissioner or Tt'aterrts Washington; D. 0.

starting position, 

